I have a MAC Pro laptop with OS X and Digital Editions 4.03 installed. I was able to activate it with my Adobe account and downloaded a file from Barnes and Nobel. Then I attempted to download a file from Books-a-Million but it does not work. I contacted them and they say I must activate using my BAM account. The documentation for Digital Editions indicates it allows multiple activations but that option is grayed out in this 4.03 So I deleted 4.03, re-installed, and activated the Books-a-Million (BAM) account That worked and I was able to download and read those books. However I no longer can access anything from Barnes and Noble. And worse, I've used up yet another Adobe activation of my six.

Help! I get ebooks from lots of on-line booksellers as well as the library. I need more than one activation option.

Your advice is good but for some reason Barnes and Noble did not show up in the vendor list when I went to re-activate.

USing my Adobe ID for DE did not allow me to open BAM Books from the ASCM file. They said I needed to use the BAM activation, so I de-activated adobe and activated BAM. That worked after I deleted DE 4.03 And re-installed. Now I could open BAM, KOBO, and library books but not books from All Romance eBooks or Barnes and Noble. All Romance Books said to de-activate BAM and activate Barnes &Noble or Adobe ID. Well, I deactivated BAM and was able to enter the Adobe ID again since the list of vendors did not include Barnes and Noble. Now I can open all of the books already in my library for the listed vendors. However, I did not test if I can open the ASCM files for all of them. Actually I cannot yet figure out how to get a nook book onto this MAC.

Suggest you consult Kobo.com support. My Mac has two USB ports so I know it can be done. I also know the operating system options must be tweaked to even see all of the files and their extensions. I believe once you find the files there is a drag and drop process involved.

But I currently have a broken nook so I cannot test the theory.

I remember seeing instructions in one of the forums during my recent search. It may be this one.